This invention relates to a printer method and system which utilizes means for generating ink droplets on demand under control of a suitable character generating apparatus.
Ink jet printing has been known in the prior art including systems which use a pressure generated continuous stream of ink which is broken into individual drops by a continuously energized transducer. The individual drops are selectively charged and deflected either to the print medium for printing or to a sump where the drops are collected and recirculated. Examples of these pressurized systems include U.S. Pat. Nos. 3,596,275 to Sweet, and 3,373,437 to Sweet et al. There have also been known in the prior art ink jet printing systems in which a transducer is used to generate ink drops on demand. One example of such a system is commonly assigned U.S. Pat. No. 3,787,884 to Demer. In this system the ink is supplied to a cavity by gravity flow and a transducer mounted in the back of the cavity produces motion, when energized by an appropriate voltage pulse, which results in the generation of an ink droplet. A different embodiment of a drop-on-demand system in which the transducer is radially arranged is shown in U.S. Pat. No. 3,683,212 to Zoltan. The prior art drop-on-demand printing systems have been limited by a low drop production rate and by a low jet stability which produced drops with irregular spacing and/or size which led to poor print quality.